The present invention relates to a brightening method for parts of aluminum or aluminum alloy.
Aluminum parts such as aluminum stampings or rolled sections are used, inter alia, in the hardware and lighting industries or, in particular, in automobile manufacture, for example, for window mounting systems or else as ornamental frames, ornamental moldings and the like. In this connection it is also known to use parts of aluminum or aluminum alloy which have a colored anodized surface. In such case, the parts are as a rule subjected to a brightening treatment as a preliminary stage before their coloring (both in natural color and also colored). One known brightening treatment for aluminum or aluminum-alloy parts is the so-called "Brytal" method (see Wernick, Pinner "Die Oberflavon Aluminium" [The Surface Treatment of Aluminum] 1969, p. 84). However, it has been found that a glossy structure or "orange rind" disadvantageously forms on chemically brightened aluminum parts produced by the Brytal method. This disadvantage is present also when acid brightening electrolytes ar used.
The object of the present invention is to provide a method for brightening aluminum or aluminum alloy parts to produce an optimum surface reflection or brightness effect on the parts.